Ten years ago, a thirtysomething runner appeared at the sports-medicine clinic of Katherine L. Dec, M.D., complaining that when she ran outside, her lips tingled, hives broke out on her arms and neck, and her chest tightened. The symptoms vanished over the next day, but they reappeared the next time she ran. "She had seen a dermatologist and her family physician, and had tried anti-itch lotions and hypoallergenic detergents without luck," says Dr. Dec, who practices in Richmond, Virginia.

Luckily, Dr. Dec was able to uncover the culprit: exercise-induced anaphylaxis-an allergic reaction that's triggered by the combination of an allergen (in this case, pollen and weeds) and exercise. She prescribed a daily antihistamine and running on a treadmill on high pollen days.

When common health issues such as allergies, headaches, or acid reflux strike midrun, as they did Dr. Dec's patient, it is sometimes hard for you-or your doctor-to figure out and fix the problem. Here, experts offer simple solutions to six symptoms that strike runners.

The Symptom: A burning sensation in your chest or throat

The Diagnosis: Acid reflux, the bubbling up of stomach acid into the esophagus. "Vigorous exercise can cause reflux even in people who don't normally have a problem with it," says Christopher Mohr, Ph.D., R.D., an exercise physiologist and nutritionist in Louisville, Kentucky. Running jostles the contents of your stomach, and the pressure from your abdominal muscles relaxes the valve that normally keeps acid in its place.

The Fix: Avoid common trigger foods--caffeine, chocolate, mint, onions, and citrus--at least two hours before you run. Loosen your waistband and fuel belt: If they're too snug, they can squeeze open the valve that keeps stomach acid down.

The Symptom: You finish a race and your head is pounding

The Diagnosis: An exertion headache, essentially a tension headache that occurs when neck and shoulder muscles tighten and restrict blood flow to the head.

The Fix: Warm up your neck and shoulders with self-massage, and neck and shoulder rolls. This will increase blood flow and help prevent the fatigue and cramping in those areas that can lead to headaches, says Mohr. Also, keep your shoulders relaxed throughout your run--once per mile, shake out your arms.

The Symptom: You feel sluggish and drained during runs

The Diagnosis: If sleep deprivation or overtraining isn't to blame, your iron stores may be low. Iron is necessary for the production of hemoglobin, the protein of red blood cells that carries oxygen to your muscles. Low iron means less hemoglobin--and less energy to run.

The Fix: Ask your doctor to test your level of ferritin, a protein that stores iron in your cells. "What's normal for a non-runner might be too low for runners," Dr. Dec says. "Ferritin levels below 30 ng/ml for women and below 40 ng/ml for men can decrease running performance." Aim for up to 27 milligrams (mg) of iron daily from beef, fish, and poultry, which your body absorbs better than the plant-based iron found in fortified cereals, soybeans, and kale, Dr. Dec says. Your doctor may also recommend an iron supplement.

The Symptom: Chest tightness on a run; coughing postrun

The Diagnosis: Exercise-induced asthma, a condition brought on by the constriction of the muscles surrounding bronchial tubes. At rest, you breathe through your nose, which warms and humidifies air. When you're running and breathing through your mouth, the air that hits your lungs is colder and drier, causing coughing, wheezing, and shortness of breath.

The Fix: Walk or jog for five minutes before picking up your pace to give your lungs time to adjust to the effort of running, Dr. Dec says. When your lungs are warmed up gradually, they can handle a heavier breathing rate easier. A vitamin C supplement may help, too. An Indiana University study found that students who took 1,500 mg of vitamin C for two weeks cut their asthma symptoms in half.

The Symptom: Itchy bumps, wheezing, feeling flushed or tingly

The Diagnosis: Exercise-induced anaphylaxis is an allergic reaction (to food, medication, clothing, detergent, or pollen) that's set off by physical activity. "It's the combination of the allergen and exercise that causes the reaction-although we're not sure why," Dr. Dec says.

The Fix: Seek medical attention if you have these symptoms-severe cases of anaphylaxis can cause facial swelling and difficulty breathing, says Dr. Dec. To help your doctor pinpoint the cause, keep a log of where you ran, what you were wearing, and what you ate beforehand. Once you identify your allergen, limit your exposure to it within two hours of running. Taking an antihistamine like Alavert or Claritin before running can also help.

The Symptom: Abdominal Pain, bloating

The Diagnosis: Gas. During an intense bout of exercise, blood moves from the digestive tract to the legs, leaving less blood to help with digestion.

The Fix:Fruits, beans, and vegetables- great foods for runners-contain fiber and sugars that commonly lead to gas. Dairy and wheat can also cause trouble, especially if you're intolerant or allergic. Eliminate these foods from your diet one at a time for a week to see if your symptoms ease. Then avoid the offenders at least four hours before you run, says Mohr. Also, check your energy-bar labels. Sugar substitutes sorbitol and mannitol, often used as sweeteners, are gas-producers. Bars like Clif Nectar and Larabar don't contain these sugars. Mohr also recommends water over sports drink because it's easier to digest.

Feel Better

Acid reflux on the run? Over-the-counter medications like Zantac, Tagamet, or Pepcid reduce acid production. Pop one a few hours before running.

Cold winter air worsens exercise-induced asthma. Wearing a face mask or scarf will warm the air before you breathe it.